Brake Pedal Excessive Travel
Step
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Action
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Yes
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No
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DEFINITION: Brake pedal travels further than expected to obtain
firm pedal and/or firm pedal cannot be obtained, pedal fades away,
or pedal is spongy.
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1
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Were you sent here from the Hydraulic Brake Symptom table?
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Go to Step 2
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-
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2
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Inspect the travel and feel of brake pedal applies. Perform the
following:
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1. |
Apply the brake pedal several times to fully
deplete the power reserve. |
|
2. |
With power reserve depleted, apply the brake pedal
with light, steady pressure and hold for 15 seconds. Observe pedal
travel and feel. |
|
3. |
Apply the brake pedal with light, steady pressure,
then without pumping the pedal, reduce pressure and reapply
pressure several times. Observe pedal travel and feel for each
apply. |
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4. |
Apply the brake pedal slowly, then release and
apply the pedal quickly. Observe pedal travel and feel for each
apply. |
Did you complete the brake pedal travel and feel inspections?
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Go to Step 3
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-
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3
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1. |
Inspect the hydraulic brake system for the
conditions listed, based on the following symptoms observed during
the pedal travel and feel inspections. |
| |
- |
Air in hydraulic system |
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External brake fluid leaks |
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Soft, weak or damaged hydraulic hoses; expanding under
pressure |
| • |
Pedal fell away and/or traveled to or almost to
floor. |
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External brake fluid leaks |
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Poor brake fluid quality; low boiling point |
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Internal brake fluid leaks; improperly functioning master
cylinder |
| • |
Pedal was somewhat firm then dropped slightly, or
pedal rose with successive applies, or pedal travel was different
between slow and quick applies. |
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- |
Internal brake fluid leaks; improperly functioning master
cylinder |
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- |
Poor brake fluid quality; low boiling point |
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Binding wheel cylinder pistons, if equipped |
| • |
Pedal returned to rest slowly after any of the
applies. |
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Internally damaged flexible brake hoses; hindering fluid
return |
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Binding caliper pistons |
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Binding wheel cylinder pistons, if equipped |
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Internal brake fluid leaks; improperly functioning master
cylinder |
|
3. |
Re-inspect brake pedal apply travel and feel. |
Did you find and correct a condition?
|
Go to Step 8
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Go to Step 4
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4
|
|
1. |
Inspect the disc brake system for the following
conditions: |
| • |
Cracked, excessively worn or damaged linings |
| • |
Cracked, excessively worn or damaged rotors |
| • |
Improperly operating, binding or damaged caliper
hardware and/or lining hardware |
| • |
Loose or missing caliper hardware and/or lining
hardware |
| • |
Excessive assembled lateral runout (LRO) of rotor
friction surfaces |
| • |
Bent or damaged caliper or mounting component |
|
3. |
Re-inspect brake pedal apply travel and feel. |
Did you find and correct a condition?
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Go to Step 8
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Go to Step 5
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5
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Inspect for proper brake pedal travel.
Is the brake pedal travel distance within the acceptable
limits?
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Go to Step 7
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Go to Step 6
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6
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1. |
Inspect for worn, missing, misaligned, bent or
damaged brake pedal system components. |
| • |
Inspect the brake pedal bushings for binding,
excessive wear and/or damage and inspect the brake pedal for a
misaligned, bent, and/or damaged condition. |
|
2. |
Replace the brake pedal system components that are
worn, missing, misaligned, bent or damaged. |
Did you find and replace any worn, missing, misaligned, bent or
damaged brake pedal system components?
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Go to Step 8
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Go to Step 7
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7
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1. |
Inspect the brake assist system for the following
conditions: |
| • |
Vacuum leaks and/or improperly operating check
valve, if equipped with vacuum assist |
| • |
Power steering fluid leaks, if equipped with
hydraulic power assist |
| • |
Damaged or improperly operating brake booster
assembly |
Did you find and correct a condition?
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Go to Step 8
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-
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8
|
|
1. |
Install or connect components that were removed or
disconnected during diagnosis. |
Is the condition still present?
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Go to Step 2
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System OK
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